466,566. Internal grinding machines. JUNG, K., (trading as JUNG MASCHINENFABRIK, K.). Nov. 27, 1935, No. 32958. Convention date, March 28. [Class 60] In an automatic internal grinding machine all the movements for feeding the grinding tool, work, and trueing tool are controlled by cams or the like mounted on a shaft which makes one complete revolution during one working cycle. In the apparatus shown the work-table 1 is reciprocated hydraulically by a piston 2 moving in a cylinder 3 supplied with fluid by a pump 9 through a control valve 12, a throttle valve 14, and a reversing valve 16. A pump 21, preferably on the same shaft as the pump 9, supplies fluid to a hydraulic gear 23 operating pawl and ratchet mechanism 28, 28<a> to rotate a shaft 30 which carries a number of cams 31 ... 37 and drives a shaft 41 carrying a cam 41<a>. The work is first subjected to a rough grinding, the fluid flow to the cylinder 3 being reversed periodically by the engagement of adjustable dogs 4, 5 on the table with a pivoted abutment 6 on a lever 7 operating the valve 16 and the grinding wheel being fed by the operation of the cam 41<a>. At the end of the roughing operation the cam 32 operates a lever 48 to turn an eccentric 51 and thereby operates a rod 52 to raise the abutment 6 out of the path of the dog 5. The table 1 consequently moves to the left beyond the normal working stroke. During this movement the cam 36 operates a lever 104 to raise a rod 103 and the cam 35 operates a lever 109 to move the rod 103 first away from a stop 102 and then into contact with a stop 101. The valve 14 which is connected to the rod 103 by a lever 97 and a rod 107 is thereby operated to reduce the fluid flow to the cylinder 3 to the speed rate required for the finishing operation. The cam 37 also has operated a lever 73 to raise a push rod 72 into the path of a lever 69 which is operated by a cam 46 on the table 1 to move the valve 12 to divert the fluid flow through a passage 76 regulated by an adjustable throttle valve 77. The lever 73 also actuates a lever 79, one arm of which raises a rod 84 to form an abutment for an arm 85 and so causes a trueing device 87 to be brought into the path of the grinding wheel and the other arm acts through pawl-and-ratchet gearing 89, 89<a> to give the requisite feed for the trueing operation to the grinding wheel. A dog 42 on the table 1 next operates a lever 43<a> actuating a pawl 54 engaging a tooth on the cam 33, the operation of the hydraulic gear 23 being stopped during this actuation by means of a valve 24 operated by the cam 34. After trueing the abutment 6 is returned to its initial position by the operation of the cam 32 and is engaged by a stop 121 on the table so that the direction of the table movement is reversed. The trueing device is returned inoperative to its inoperative position by a cam 93 on the machine frame and the valve 12 is returned to its initial position by a spring 119 on the disengagement of the cam 46 with the lever 47 operating the lever 69. When the dog 42 engages with the lever 43<a> the valve 24 will be closed and the shaft 30 will be given a further rotational movement by the pawl 54. During this movement the cam 31 operates a lever 56 to move a rod 59 in front of anode 60 on a rod 55 connected to a lever 45<a>. The finishing operation now takes place and on its completion the cam 32 again raises the stop 6 and the table moves to the left until the cam 42 operates the lever 43<a> to turn the shaft 30 by means of the pawl 54. During this movement the valve 24 is closed by the cam 34, the stop 6 is released by the cam 32, the lever 109 is moved into engagement with a stop 111 by the cam 35, and the rod 103 is moved opposite the roughing stop, 102 by the cam 36. The table then moves to the left until a cam 44 on the table operates a lever 45<a> to move the rod 55 to the right and the stop 121 on the table engages the stop 6 and so operates the reversing valve 16. The movement of the rod 55 causes the rod 59 to open a valve 63 providing an escape for the fluid supplied by the pump 9 so that the table is brought to rest. When a fresh piece of work has been clamped to the table the machine is restarted by pressing a knob 64 which lifts the rod 55 and allows a spring 66 to close the valve 63. As the table moves to the right the dog 42 engages the lever 43<a> and the pawl 54 turns the shaft 30 sufficiently to cause the cam 34 to open the valve 24 and put the gear 23 into action. When desired the shaft 30 may be rotated by a hand wheel 120, the cams, other than the cams 32, 36, 41<a> being rendered inoperative by turning a cam shaft 112. The lever 97 is pivoted on a pin 100 mounted on an eccentric which may be turned by a handle 99 to adjust manually the throttle valve 14. The grinding wheel may be suspended in a cradle as described in Specification 386,885.